The following are some of the most common habits you may use to seek approval from others.
Once you're aware of what you're doing, it's then just a matter of changing your behaviour.

Judging Others
When you walk into a room full of people, what’s the first thing you do?

Is it to size everyone up and think, “Oh, she looks mean” or
“He’d never talk to me” or “That’s the popular group, better not make
eye contact with any of them”. If you are, then you're trying to judge
people before they can judge you.

By pre-judging people, you cause a lot of your own grief and make
yourself feel much worse than you need to. You don’t want people to
judge you yet you’ve gone ahead and pre-judged them. Stop judging and
just be in the moment. Remember that everyone has so much more to offer
than what you see at first glance. (Watch my Confidence Secrets video for more on this)

Trying to Impress Others to Make Them Like You
You’ve probably heard sayings like, “You have 10 seconds for someone to
make up their mind about you” and “You need to impress people to get
them to like you.” By thinking this way, you put a lot of unneeded
stress on yourself.

Also, think to a time when you first met someone and you knew they were trying so hard to get you to like them.

How did you feel about that?

Most likely, it put you off because they were trying too hard.
You would have liked to have them just be themselves, to relax, and be
natural. Or it may make you feel suspicious about them as in why are
they trying so hard? Do you see what I mean? If you try to impress
people, most likely you won’t. If you relax and just be yourself, you
will impress people.

Trying to impress others also means that you miss out on a lot.
You won't hear large parts of conversations because you tune the other
person out while you try to think of something clever or witty to say or
think about what story you know which will beat their tale. You'll be
so intent on your own image that you don't simply enjoy the conversation
or hear what that person has to say or even get to know that other
person. You become so focused on yourself that nothing else matters.

For your efforts to gain approval, all you'll end up with is
feeling empty and insecure. You’ll probably rerun the event over and
over in your head thinking you weren’t good enough. If you hadn’t
worried about impressing others but rather concentrated on the moment,
you might have made a new friend, or learned something valuable, or just
had a good laugh about something. You would then have good
memories of the event instead of beating yourself up over it.

Adding Your Own Beliefs To What You Hear
You may feel you don’t have someone’s approval when really you do.
The other person just hasn’t said anything or you may be reading
something into the situation that isn’t there. The temptation might be
to start thinking about what ulterior motives they have for what they
say. For example, if someone gives you a compliment, you may also be
adding your own story to it. You may think, “They’re only being nice to
me because they feel sorry for me.” Let your life story go and just listen to people and what they say literally. Don’t add your own beliefs to it.

“Our interpretations of what we hear people say to us are often
far more painful or frightening than what people actually say. We can
hurt ourselves with our misconceptions and our thinking for others.” -
Byron Katie

Not Minding Your Own Business
What you think and what you choose to spend your time thinking about is
completely your own business. What someone else thinks is their own
business. You wouldn’t want someone else telling you what to think, so
why do you try to control other people’s opinion of you? They’re allowed
to think whatever they want. That’s their right. Just as it’s your
right to have your opinion. So, don’t worry about what others think,
just respect their opinion. You don't have to agree with it, just
respect that they're entitled to their own thoughts.

Instead, ask yourself, “Is this something I approve of myself for doing?” It’s your opinion which matters the most.

If you’re busy thinking what someone else should be doing, then
you’re not paying attention to your own business. As soon as you say
things like, “He should spend more time with me”, “She should appreciate
what I’ve done for her”, or “He should get a better job”, you are not
minding your own business.

Life is just so much easier if you just concentrate on what you
need to do. Other people can take care of their own lives. You just need
to focus on your own. So, the next time you start thinking, "He should
listen to me", tell yourself, to mind your own business and then ask
yourself, "What should I be doing?". In this case, the answer most
likely will be something like, "I should be listening to me." It's actually quite interesting in that often the advice you give to others, is really the advice you should be giving to yourself.

You may also be distracting yourself from dealing with your own
issues by focusing on what you think needs to be fixed in someone else's
life. You ignore your own needs. Focus on your own life. Pay
attention to what it is that you want and what you need. By doing this,
you will gain approval from others because you know what you want.
People respect those that know what they want.

What if they don’t approve of you?
Do you really need this person’s approval? Will you stop breathing and
die if you don’t get it? Of course not. You may be putting too much
emphasis on someone else's opinion. It really doesn’t matter what they
think as long as you’re happy with what you’ve done.

Focus on others or the present moment
If you find that you’re afraid of saying something because you’re
worried people will think your comment is stupid, well stop thinking
about yourself. Think about the situation. Be in the present moment.
What are they discussing? Focus on that.

Being Overly Polite
Do you make excuses or apologies in order to defend yourself or give a better opinion of yourself?

Even though we think that being polite is about being considerate
of others, many times it's about trying to create a better impression
of yourself. It's not your fault the document isn't finished or that you
were late or that you forgot to pick someone up. Usually, it's all an
attempt to manage your self image. Pay attention to what excuses you're
providing and then ask yourself why you feel the need to do this.

Breaking Your Approval Habits is Worth It
Once you understand that searching for approval in others is really a
clue to what you need to give yourself, you'll feel an
overwhelming sense of relief.

You can now simply enjoy conversations with others without
stressing yourself out trying to think of something clever or witty to
say. You won’t interrupt people and will calmly let them finish their
sentences, you won’t be tuning out, you won’t be apologizing or making
excuses for your actions. This will all instantly disappear because you
no longer need approval from others.

Your self esteem will rise instantly by leaps and bounds. Your
whole life will be completely different. So, let it go and just know,
YOU DON’T NEED anyone else's approval because you approve of you. And,
that's one of the biggest secrets to enjoying life. Give yourself what
you need and you will get it from others.

An average man is too concerned with liking people or with being
liked himself. A warrior likes, that’s all. He likes whatever or
whomever he wants, for the hell of it. - Carlos Castaneda

I Need Your Approval Video

If you're an approval seeker, you'll most likely relate to the people in
this Byron Katie video and what they say happens when they search for
approval in others. It gives you some additional motivation on why you
want to stop seeking approval from others.

Additional Resources

These are two fantastic books on how to work through your thoughts and see how you really don't need any one else's approval. Just your own.

Leonard Nimoy's Inspirational Letter

In 1968, Leonard Nimoy (better known as Spock in the Star Trek series) responded to a fan who wanted to know how he handled not fitting in. Some of the gems from this letter are, "But it was only the need for popularity that was ruining his happiness. The question was which was more important, was being 'popular' with the pack who might turn on him any minute or being true to himself?" Read the full article here or on My Star Trek Scrapbook.